Bibcode
Balcells, M.; Morganti, R.; Oosterloo, T.; Perez-Fournon, I.; Gonzalez-Serrano, J. I.
Bibliographical reference
Astronomy and Astrophysics, v.302, p.665
Advertised on:
10
1995
Journal
Citations
13
Refereed citations
9
Description
We study the orbital properties of dumbbell galaxies which harbor
twisted radio jets. Velocity and velocity dispersion profiles for four
dumbbell pairs (3C66B, 3C75, 3C449, 0326+39) are presented. We analyze
optical CCD images in search of isophote off-centering and large
isophote twists. Combining the kinematic and isophotal information, we
discuss whether each system is an interacting pair, and derive
constraints on the relative orbit. The types of isophotal distortions,
combined with the prograde/retrograde nature of the relative orbit,
suggest that three of the objects (3C66B, 3C75 and 0326+39) are unlikely
to be in circular orbits. Only 3C449 may be in a close,
moderate-ellipticity orbit. We find that the distribution of relative
velocity with separation for dumbbells with distorted radio morphology
from the catalogue of Parma et al. (1991) also suggests a prevalence of
eccentric orbits. We discuss that dumbbells with distorted radio
morphology may deviate significantly from the circular orbit model
proposed by Valentijn & Casertano (1988). The genesis of radio
distortions could be related to such distinct orbital behaviour. The
amplitude and wavelength of jet oscillations in these objects correlates
with the projected separation of the pairs, pointing at a dynamical
origin for the jet oscillations. However, for three of the four systems
studied in detail here, the jet oscillations cannot be easily traced to
orbital displacements of the parent galaxies. Either interactions
trigger radio beam precession, or the intracluster medium plays a role
in setting the radio beam oscillations.